It is well known in the art that repeated washing of cotton-containing fabrics generally causes a pronounced, unpleasant harshness in the fabric, and several methods for overcoming this problem have previously been suggested in the art. For example GB 1,368,599 of Unilever Ltd. teaches the use of cellulytic enzymes for reducing the harshness of cotton-containing fabrics. Also, U.S. Pat. No. 4,435,307 (of Novo Industri A/S) teaches the use of a cellulytic enzyme derived from Humicola insolens as well as a fraction thereof, designated AC.sub.x I, as a harshness reducing detergent additive. Other uses of cellulytic enzymes mentioned in the art involve soil removal from and colour clarification of fabric (cf. for instance EP 220 016), providing increasing water absorption (JP-B-52-48236) and providing a localized variation in colour to give the treated fabrics a "stone-washed" appearance (EP 307,564). Cellulytic enzymes may furthermore be used in the brewing industry for the degradation of .beta.-glucans, in the baking industry for improving the properties of flour, in paper pulp processing for removing the non-crystalline parts of cellulose, thus increasing the proportion of crystalline cellulose in the pulp, and for improving the drainage properties of pulp, and in animal feed for improving the digestibility of glucans.
The practical exploitation of cellulytic enzymes has, to some extent, been set back by the nature of the known cellulase preparations which are often complex mixtures. It is difficult to optimise the production of multiple enzyme systems and thus to implement industrial cost-effective production of cellulytic enzymes, and their actual use has been hampered by difficulties arising from the need to apply rather large quantities of the cellulytic enzymes to achieve the desired effect on cellulosic fabrics.
The drawbacks of previously suggested cellulase preparations may be remedied by using preparations comprising a higher amount of endoglucanases. A cellulase preparation enriched in endoglucanase activity is disclosed in WO 89/00069.